Cheating is obviously a big issue, so 3d-shooters has slapped up a Cheating Article.. It's quite interesting, here's a blurb:
Well in reality there really is no true "Head Shot Script". The only this that this script would do is freeze your aim at head shot level, but it's up to you to aim and fire the weapon. It is truly impossible to have a real Head Shot Script that does all the work. It was explained to me like this. To make the head shot script you would have to program it so that it would know where the head is (not easy) then you would have to make it so that it takes over the controls pulls your character over and shoot the person in the head. Doing this all the time and making it sure that the script (or crack) would know who is your enemy or friend would take a hell of allot of system power and slow you down. The only way to get a head shot is with really good aim or a little luck (which seems to be happening with me).